Introduction: Wilderness or backcountry diarrhea is a type of travelers’ diarrhea commonly caused by Cryptosporidium and Giardia, which can survive freezing temperatures. Campsites pose additional risks worldwide, irrespective of developing or developed regions, due to inadequate hygiene.Methods: In a first of its kind, an outbreak of wilderness diarrhea at a semi-permanent Himalayan Base Camp at 4000 m/13,125 ft in Uttarkashi, India, was investigated and managed by empirical antimicrobials. Return of normal bowel function was considered as primary outcome, and return to routine training at Base Camp was considered secondary outcome.Results: Sixty-two personnel presented with wilderness diarrhea of 5.58 days mean duration with onset after mean stay of 10.26 days, despite provisions for adequate camp hygiene and sanitation. Both primary and secondary outcomes were reached by all except three students who were evacuated on foot to the district referral hospital 56 km downhill from Base Camp. Hygiene was compromised due to cold weather/water. Epidemiological surveillance was not contributory.Conclusion: Wilderness diarrhea can present in outbreak proportions from formerly safe water sources due to variable microbial contamination. On-site diagnostics and management are required to control outbreaks of wilderness diarrhea. Traveler risk management strategies and traveler awareness/education can be a targeted mandatory intervention to enhance preparedness and resilience capital in outdoor and mountain environments.